Mixer for cement or the like

ABSTRACT

A MIXER IN PARTICULAR A BUILDING MATERIAL MIXER IN WHICH A RAPIDLY ROTATING WORM SCREW CONVEYOR IS MOUNTED IN A TROUGH AND THE MATERIAL ON LEAVING THE SCREW CONVEYOR IS DRIVEN AGAINST A WALL OR BAFFLE TO RECIRCULATE THE MATERIAL THROUGH THE WORM SCREW CONVEYOR.

United States Patent 2/1909 Hassam.............,..........

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Primary Examiner-Robert W. Jenkins Attorney-Edward Brosler [54] MIXER FOR CEMENT OR THE LIKE ABSTRACT: A mixer in particular a building material mixer [51] Int. Field of 179,165, 169,170, 97, 9,10, 25, 26, 45, 46

in which a rapidly rotating worm screw conveyor is mounted [56] References Cited in a trough and the material on leaving the screw conveyor is UNITED STATES PATENTS driven against a wall or baffle to r 9/1874 through the worm screw conveyor.

ecirculate the material PATENTED JUN28 9n SHEET 1 OF 3 INVENT( )R ATTORNEY PATENTEDJUN28I97I 3.588.056

' SHEET 2 0F 3 INVENTOR Pr! (/1. AUGUST LSM/ ATTORNEY PATENTEU JUN28 [9n SHEET 3 OF 3 /N l/ENTOI? FAX/L H0600"? MIXER FOR CEMENT OR THE LIKE The present invention relates to a mixer in particular a building material mixer in which a rapidly rotating worm screw conveyor is mounted in a trough.

Such mixers are in particular intended for the intensive preparation of the binding medium and the fine components. Tests have shown that cement, hydraulic lime and similar binding means with the mixing procedures in mixers known up till now are not provided with water as far as into the core. Thereby the full possibility of the solidity attainable with these binding media is not utilized.

Proposals have already been made in general literature to obviate this drawback but these have led only in the fewest cases to a certain extent to the desired results.

The mixing tools must operate such that they exercise a high pressure and high speed on the material to be mixed. Hereby the cement core is pulverized still finer and in addition the surface tension is taken by cement, the water and the fine grain of the additional materials. When this occurs firstly the total surface of the binding medium is greater and secondly the water can penetrate as far as into the core. Boundary layer formations of foreign media between the individual substances are prevented and the substances are really extremely intimately bound to one another.

So-called turbine mixers which consist-of a cylinder closed at the bottom and have near the lower end a rapidly rotating disc under same fulfill with correct construction the requirements for the high degree of exploitation binding medium. These'mixers, however, have the drawback that they can be charged and emptied only with difiiculty. With these known arrangements the charging place is higher than the emptying place whilst it should be the opposite.

For the removal of these drawbacks it is proposed according to the invention that in a trough lying inclined a rapidly rotating worm screw conveyor with direction of conveying from below upwards should terminate just before an oblique wall whereby between the end of the worm screw and the oblique wall an acute angle is formed which widens upwards. By means of this construction an intensive thorough mixing in the mixer is ensured.

According to the invention it is furthermore of advantage for a propeller-shaped disc or a disc with springs to be located at the upper end of the worm screw conveyor. Hereby it isprovided for the edges of the disc to be bevelled or bent at an angle from the front to the rear and in the direction of rotation from the rear to the front.

A further construction is seen in that the conveyor work screw consists of a band which is fixed on the shaft with clearance by means of struts. In doing so it is of advantage for the conveyor worm screw to consist of many interrupted worm screw segments.

A further construction according to the invention is seen in that above the opening there is located between the disc and the oblique wall a baffle plate.

It is furthermore possible for such a mixer to be inserted as preglue mixer for the binding medium with water, and, if necessary, also the fine grain is inserted in the lifting bucket of a building material mixer. The preglue mixer may also be fixed on the proportioning sloping wall of a mixing installation.

It is furthermore of advantage for the outlet opening to lie in the quantity measuring panel for the fine grain or the sand above the filling opening of the preglue mixer fixed on the sloping wall.

It is, of course, also possible for the mixer to be constructed in horizontal form.

A further possibility of construction consists in that the con-- veyor worm screw of the mixer conveyor from the middle to both ends and both ends are provided with an oblique wall, a baffle plate as well as an outlet opening. It is likewise possible for no outlet opening to be present on the mixer, 'for that, however, the mixer is mounted pivotally such that its upper filling opening can be pivoted downwards.

A particularly preferred construction is seen in that the worm screw threads under the material feed have about double the pitch compared with the other worm screw threads. Thereby the material which is introduced into the material feed is prevented with certainty from being thrown back.

A further suitable construction of the invention is seen in that the worm screw threads are interrupted by gaps. Thereby it is likewise advantageous for the worm screw thread to be provided with additional openings such as, for example bores. Thereby there is the possibility for the pressure of the mixed material possibly resulting due to these openings or passages of being capable of being compensated.

A further advantageous formation of the construction according to the invention is seen in that the upper bent area of the baffle wall is mounted pivotably around a horizontally mounted shaft such that in the perpendicular position it guides the material to be mixed to the worm screw, on the other hand after a pivoting leads it to the outlet funnel. Thereby an emptying slide is'practically superfluous the disposition of which hitherto always entailed considerable difficulties.

When the guide plate is in the closed position then the material to be mixed is pressed with high pressure practically by means of the worm screw conveyor against the obliquely positioned bafile plate and escapes upwards. There the material is to be mixed is then guided with the guide plate and returns to the lower end of the worm screw. This circuit continues until the guide plate is rotated about its pivot. In this case the material to be mixed is pressed automatically via the guide plate to the outlet funnel and then into the open air.

A further construction according to the invention is seen in that the mixing trough in the feeding area in the resting position lies lower than in the delivery area. It is also hereby possible for the mixing trough to be pivotably mounted in known manner whereby the pivoting can be effected via any desired driving means.

A further advantageous construction of the invention is seen in that the baffle wall is provided with a guide plate which leads back as far as the feeding place. Hereby it is advantageous for the guide plate to be formed arcuate like half an eggshell and form with the other part of the mixing trough a kind of noule.

With this construction it is likewise arranged for an outlet to be provided below the worm screw conveyor in the end area of the mixing trough. This outlet may be closed via a slide valve, tap or the like known per se. It is furthermore proposed that the speed of the worm screw conveyor be selected so high that the centrifugal force produced by the conveying speed suffices to convey the material to be mixed over the guide plate again to the screw feed.

The baffle is arranged in an angle to the worm screw. The most useful arrangement will be seen when the baffle is arranged vertically to the worm screw. It is naturally also possible to have the baffle in a sharp angle to the perpendicular in relation to the worrnserew. Thereby you have the advantage that through the perpendicular arrangement of the baffle an equal pressure up and down will be surely directed through the mixture. The outlet itself can preferably be closed over a rotary slide.

The invention will be explained in more detail with reference to the drawing which shows a few preferred embodiments. Further features of the invention follow from the drawing and description thereof.

FIG. 1 and FIG. 2 show a mixer in elevation from above and in longitudinal section built in the lifting bucket of a building material mixer.

FIG. 3 shows a cross section through a mixer.

FIG. 4 shows a special construction of the thrust disc washer. 1

FIG. 5 another construction of the mixer in side view.

FIG. 6 is a section through the worm conveyor according to FIG. 5.

FIG. 7 is a diagrammatic side view of the mixer in another construction.

In an inclined mixing trough 1, which is formed circular shaped at the bottom there is located in its lower part on a shaft 2, a conveyor screw 3 or interrupted worm screw elements 4. When it is a continuous conveyor screw then it is a question of a worm screw band 5 which is fixed with clearance on the shaft 2 with struts 6.

The direction of conveying is from below upwards. On the upper end of the conveyor screw there is located preferably a disc 7 which with its face and its edges 8 and 9 is so formed that it can exercise a high conveying and pressure force on the mixed material.

The mixing trough is provided on its upper end in the lower part in the vicinity of the disc 7 with an inclined part 10 which from below upwards to the disc produces a widening space. Above this space there is a guide plate 11. On the lower end of the inclined part there is an opening with a slide 12.

The manner of operation of the mixer is as follows:

The worm screw with the disc will be driven at a high speed (about l,000-3,000 r.p.m.). On this rapidly rotating worm screw is deposited first of all water and immediately thereupon or at the same time cement.

Water and cement is on the one hand intimately mixed by means of this worm screw and on the other hand driven upwards before the inclined part 10. The angle of inclination between the inclined part 10 and the disc 7 is such that a very high pressure is exercised, on the material in the space between the inclined part 10 and the disc 7 but the material still under high pressure and high speed is pressed out of the upper wider part of the space.

The material to be mixed is guided around on the plate 11 and guided again into the lower part of the mixing trough. There it again meets different places in the area of the rapidly rotating worm screw conveyor and is again mixed and pressed guided upwards.

Thus there results a circuit of the very rapidly moving material to be mixed which in consequence of high speed, friction and pressure most finely grinds the portions of the binding medium and at the same time allows water to penetrate as far as the core of the binding medium.

A few seconds after the binding medium and water are intensively mixed fine-grained sand or other fine-grained additional substances are deposited. This substance also, is as previously described, intimately mixed with the material already in the mixer. Thereby at the same time the surface tension is removed from all substances and a really intensive mixing without boundary layer formation of foreign substances is attained.

As such rapidly rotating mixers are not suitable for the manufacture of concrete or the like with coarse additional substances these mixers are combined with constructional elements of normal concrete mixers or mixing plant.

FIGS. 1 and 2 show the building in of such a mixer in the lifting bucket 13 of a concrete mixer.

As the cable rollers 14 for the lifting bucket is in the middle, in this construction the driving motors 15 are placed close by on the right and left. For reasons of space it is also more advantageous to use two small motors than one large motor.

Water, cement and fine gravel are placed in the lifting bucket inside the mixing trough with rapidly rotating worrn screw conveyor whilst the worm screw rotates. The coarse material are deposited in the space on the right and on the left close by 16 and 17.

As the mixer is placed in the bucket within an inclination the spaces 16 and 17 have a connection under the mixer in the lifting bucket which is of advantage upon depositing for better mixing of the different coarse additional substances. After all substances are deposited the lifting bucket goes upwards. Cement, water and fine-grained substance are in the meantime intermittently mixed with at the same time full decomposition of the binding medium.

At the moment when the lifting bucket is pivoted for emptying then at the same time by means of a mechanical release the slide 12 is so-actuated that it frees the opening. With the flowing up of the coarse additional substances the intensively mixed fine material consisting of water, binding medium and fine-grained substance flows at the same time together into the I actual mixer. Therein the shortest time a satisfactory covering of the coarse material with the premixed fine material and binding medium is affected.

The mixer for the fine substances may also be mixed on the sloping wall of a mixing plant. It is preferably placed along this sloping wall and in fact such that the outlet opening of sand goes directly above the filling opening of the mixer. In this case the outlet opening of the sand in the sloping wall is a little higher than that of the other additional substances. The mixer may also be so constructed that it is opened on this sloping wall horizontally therefore without inclination and has at both ends a disc and an inclined wall.

The conveyor screw is then so constructed that it conveys from the middle going out to both ends. The emptying of the premixer thus mounted can likewise be effected through openings at the ends or by turning the mixer so that the upper open part is pivoted downwards.

A particularly advantageous construction can be seen in FIG. 5.

The mixer consists here also of the actual mixing trough 1 in which the shaft 23 with the worm screws 30 runs, whereby the shaft 23 is guided in bearing 28 and 29. The drive of the shaft 23 is effected via a motor 25 and belt pullings 26 and a pinion 27. The material to be mixed is fed at the material feeds 24.

As can be seen from the drawing the worm screw conveyor is provided in the area below the material receiver 24 as indicated at 31 with an inclination twice as great as the following area of the wonn screw 30. Thereby the material introduced via the material feed being thrown back again to the material feed 24 is avoided. The material itself is pressed at the end of the worm screw conveyor against a baffle plate 22 which is arranged at an angle to the support of the mixing trough 1, it is pressed from there upwards and then guided back via a guide plate 19 with the position shown, to the worm screw 30. If on the other hand the guide plate 19 is rotated or pivoted about the pivot 18 into the position shown in broken lines then the material conveyed by the worm screw conveyor is fed to the outlet funnel 20 and can be suitably removed from there.

As can be seen in FIG. 6 for compensation of the pressure within the worm screw conveyor this can be provided with slits 32 and also with bores 33 in order to avoid too great a tension within the worm screw. The size of the slits 32 and also of the recesses 33 may be selected as large as desired corresponding to the material to be used.

The pivot 18 of the guide plate 19 is thereby so disposed that the guide plate 19 inside the outlet funnel 213 has a form connection. Thereby a satisfactory guiding of the material to be mixed is ensured.

An intermediate crosspiece is indicated at 21 which connects the baffle plate 22 to the outlet funnel 20.

As can be seen in FIG. 7 the guide plate may also as indicated at 42, be formed by the baffle plate direct in eggshell like construction and thereby convey the material to be mixed when the mixing trough 8 is closed, back to-the supply point. It is a question hereby practically of a so-called feedback as the material to be mixed is conveyed by the worm screw in the direction of the arrow 36 and then so indicated by the arrows 37, 38, 39, 40 and 41, it is again conveyed back to the supply point of the worm screw.

The feed point itself is indicated at 24 and the direction of throwing in of the material to be mixed is indicated at 35 by means of an arrow.

The removal of the finished mixed material is effected in this case at the underside of the mixing trough 8 at an extractor 34 which is located at the same time under the shaft 23 and on the edge of the baffle plate 22.

Thebaffle sheet which is arranged at a sharp angle can also be, which is not shown for simplicity's sake, set exactly vertically to the worm screw. The result will be that the material stream meeting with the baffle will be forced equally up and down so that an opening for removal situated underneath will be supplied with sufficient mixture.

Otherwise the apparatus corresponds exactly with the construction as described in the other FIGS. of the drawings.

It is of course also possible to effect these modifications in the embodiment without however departing from the ideas of the present invention.

1 claim:

1. A mixer for materials such as a pulverized binding medium and water, comprising means for thoroughly mixing such binding medium and water to a paste consistency, said mixing means having a discharge end, and means for exerting pressure on such paste sufficient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, such pressure-exerting means including a pressure wall in proximity to the discharge end of said mixing means, a propellerlike disc at the discharge end of said mixing means, and means for driving said mixing means and propellerlike disc at a speed such that the mixture is pressured against said pressure wall by said propellerlike disc with a pressure sufficient to break down surface tensionof the water and pressure drive said water deep into the particles of the binding medium.

2. A mixer in accordance with claim 1, characterized by said means for mixing such binding medium and water as including a substantially horizontal trough and a mixing screw conveyor in said trough, and said pressure-exerting means as including a substantially vertical pressure wall in proximity to the discharge end of said mixing screw conveyor, and means for driving said mixing screw conveyor and propellerlike disc at a speed such that the mixture is pressured against said pressure wall with a pressure sufficient to break down surface tension and pressure drive said water deep into the particles of said binding medium.

3. A mixer in accordance with claim 2, characterized by said trough and mixing screw conveyor being slightly inclined with its discharge end uppermost.

4. A mixer in accordance with claim 2, characterized by said propellerlike disc being on the discharge end of said mixer screw conveyor for rotation therewith, to build up pressure against said pressure wall.

5. A mixer in accordance with claim 4, characterized by a guide plate supported above the opening between said propellerlike disc and said pressure wall.

6. A mixer in accordance with claim 5, characterized by said pressure wall leaning slightly in a direction away from said mixing screw conveyor to guide such pressurized mixture into vertical movement.

7. A mixer in accordance with claim 5, characterized by a discharge opening adjacent said pressure wall, and means for arbitrarily blocking said opening during a mixing operation.

8. A mixer in accordance with claim 2, characterized by a lift bucket for holding aggregate and said mixer installed in said lift bucket, said mixer trough having a normally closed but openable discharge opening from said trough into said lift bucket whereby upon tilting said lift bucket and opening said normally closed opening, the aggregate and binding mixture may be discharged to any suitable concrete mixing apparatus.

9. A mixer for materials such as a pulverized binding medium and water, comprising means for thoroughly mixing such binding medium and water to a paste consistency, said means including a substantially horizontal trough and mixing screw conveyor in'said trough, means for exerting pressure on such paste sufficient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, said pressure-exerting and driving means including a substantially vertical pressure wall in proximity to the discharge end of said mixing screw conveyor, and means for driving said mixing screw conveyor at a speed such that the mixture is pressured against said pressure wall with a pressure sufficient to break down tension of the water and pressure drive said water deep into the particles of said binding medium saidpressure wall leaning slightly in a direction away from said mixing screw conveyor to guide such pressurized-mixture into vertical movement.

10. A mixer in accordance with claim 9, characterized by means for returning said vertically moving pressurized mixture back to said mixing screw conveyor.

11. A mixer in accordance with claim 10, characterized by said means for returning said pressurized mixture to said mixing screw conveyor, including a guide plate forming an effective continuation of said pressure wall and so directed as to guide pressurized mixture back to said mixing screw conveyor for additional treatment.

12. A mixer in accordance with claim 11, characterized by an outlet funnel from said trough, and means for changing the direction of said guide plate, from said mixing screw conveyor to said outlet funnel to provide for discharge from said trough, of pressured mixture.

13. A mixer for materials such as a pulverized binding medium and water, comprising means for thoroughly mixing such binding medium and water to a paste consistency, said means including a substantially horizontal trough and mixing screw conveyor in said trough, means for exerting pressure on such paste sufiicient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, said pressure-exerting and driving means including a substantially vertical pressure wall in proximity to the discharge end of said mixing screw conveyor, and means for driving said mixing screw conveyor at a speed such that the mixture is pressured against said pressure wall with a pressure sufficient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, and means for arbitrarily blocking release of such pressurized mixture from said trough, whereby pressure developed against said pressure wall will be maximum.

M. A mixer for materials such as a pulverized binding medium and water, comprising means for thoroughly mixing such binding medium and water to a paste consistency, said means including a substantially horizontal trough and mixing screw conveyor in said trough, means for exerting pressure on such paste sufficient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, said pressure-exerting and driving means including a substantially vertical pressure wall in proximity to the discharge end of said mixing screw conveyor, and means for driving said mixing screw conveyor at a speed such that the mixture is pressured against said pressure wall with a pressure sufficient to break down surface tension of the water and pressure drive said water deep into the particles of said binding medium, said mixing screw conveyor having twice the thread pitch at its intake end than toward its discharge end and the threads of said screw conveyor having openings therein. 

